9mm vs .38 Special

Quick comparison

This comparison is really about platforms

Unlike 9mm vs .45 ACP or 9mm vs .40 S&W — where both cartridges fire from the same type of gun — 9mm vs .38 Special is fundamentally a semi-auto vs revolver debate. The cartridge characteristics matter, but the platform differences matter more.

Cost per round

Surprisingly close. 9mm FMJ runs $0.17–0.25/rd. .38 Special FMJ runs $0.20–0.34/rd. The gap is smaller than most people expect.

.38 Special benefits from high production volumes (millions of revolvers in circulation) and simple cartridge construction. It's the cheapest revolver caliber by a meaningful margin — and that's one of its core advantages.

For defense ammo, .38 Special is actually cheaper on average. Standard .38 Special JHP runs $0.45–0.85/rd vs 9mm JHP at $0.55–1.00/rd. .38 Special +P defense loads from Speer Gold Dot and Federal HST run $0.50–0.90/rd.

Compare 9mm prices → | Compare .38 Special prices →

Ballistics

9mm is noticeably more powerful than .38 Special — roughly 30–50% more muzzle energy depending on the loads compared.

Standard .38 Special (non +P) from a 2" snub-nose revolver produces roughly 170–200 ft-lbs. This is on the low end for effective self-defense — JHP expansion is not guaranteed at these velocities. .38 Special +P loads add 10–15% more velocity, pushing energy to ~240–260 ft-lbs and making JHP expansion more reliable.

9mm from a 3" micro-compact barrel produces 310–350 ft-lbs — well above the threshold for consistent JHP expansion.

The .38 Special +P imperative: For self-defense from a snub-nose revolver, +P ammunition is strongly preferred. Standard-pressure .38 Special operates at velocities where many JHP designs fail to expand. Speer Gold Dot 135gr +P Short Barrel is specifically designed for snub-nose revolvers and is among the most consistent-performing .38 Special defense loads in gel testing.

Capacity and reloads

This is the largest practical difference:

A Sig P365 carries 10+1 rounds of 9mm in a package barely larger than a S&W J-frame revolver carrying 5 rounds of .38 Special. With an extended magazine, the P365 holds 15+1 — three times the capacity.

Reloading compounds this. A semi-auto magazine swap takes 1–2 seconds with practice. A revolver reload with a speedloader takes 3–5 seconds under stress. Speed strips take longer. In any realistic defensive scenario, the revolver's capacity and reload speed are significant disadvantages.

Revolver advantages

Despite the capacity and power disadvantage, revolvers have real strengths:

Simpler manual of arms. No magazine to fumble, no slide to rack, no tap-rack-bang drill to learn. Pull the trigger, the cylinder turns, the gun fires. That said, revolvers aren't immune to malfunctions — a high primer or a bullet that jumps crimp under recoil can lock the cylinder, and that's a gunsmith fix, not a field-clearable stoppage. A quality semi-auto with good magazines is just as reliable in practice.

Enclosed-hammer simplicity. Snub-nose revolvers like the S&W 642 (Airweight) have an enclosed hammer and no safety to disengage. Draw, point, press trigger. The manual of arms is the simplest of any defensive firearm.

Ammunition flexibility. .38 Special revolvers can fire any .38 Special load. .357 Magnum revolvers can fire both .38 Special and .357 Magnum — cheap practice ammo and full-power carry ammo from the same gun.

The .357 Magnum upgrade path

Any revolver chambered in .357 Magnum also fires .38 Special — the .357 case is just slightly longer, so it fits the longer .357 cylinder but won't chamber in a .38-only gun. If your revolver is chambered in .357 Mag, you get:

• Cheap .38 Special ($0.20–0.34/rd) for practice
• Full-power .357 Mag ($0.55–1.10/rd) for carry — delivering ~580 ft-lbs, which exceeds 9mm by a wide margin

This combination — .38 Special training / .357 Mag carry — is the most cost-effective revolver setup and one of the strongest arguments for the revolver platform.

When each caliber makes sense

Pick 9mm if:

• Maximum capacity matters
• Faster reloads under stress are a priority
• You want the widest selection of guns and accessories
• You want maximum ballistic performance from a compact package
• Training volume and cost matter (though the gap is small)

Go with .38 Special if:

• You prefer the simplicity and reliability of a revolver
• You want the .357 Magnum upgrade path
• Mechanical simplicity is a priority (no slide, no magazine)
• The shooter is more comfortable with a revolver manual of arms
• Backup gun or nightstand gun where extreme simplicity matters

Related comparisons

• 9mm vs .357 Magnum — 9mm vs the revolver's full-power option
• 9mm vs .45 ACP — The classic semi-auto caliber debate
• 9mm vs .380 ACP — Carry caliber comparison

Related caliber pages

• 9mm ammo prices — Current pricing across all retailers
• Cheapest 9mm right now — Lowest observed prices
• 9mm price history — 30-day pricing trends
• .38 Special ammo prices — Current pricing across all retailers
• Cheapest .38 Special right now — Lowest observed prices
• .38 Special price history — 30-day pricing trends
• .357 Magnum ammo prices — The .38 Special's big brother
• .38 Special +P — Higher-pressure defense loads

Search 9mm ammo → | Search .38 Special ammo →